Today acceptable barrier properties in textile and nonwovens have been generally achieved by laminating breathable or non-breathable film to a nonwoven or textile. Eliminating such a lamination process while maintaining the desired transport and barrier properties is sought so that costs can be reduced while maintaining the textile touch.
In the past few years there has been a significant development in Spunbond technology driven by machine manufacturers in order to cut cost in the hygiene market for producing spunbond nonwovens. Due to the ever increasing rates of production, machines are currently been installed with up to 6 beams with 7 beam machines as the next generation. These machines typically have Spunbond and Meltblown beams in combination.
Therefore, when looking to replace the lamination step for combining films with the nonwoven, it was decided to produce a structure inline utilizing the newer multibeam technology and include a low melting polymer in the one or more of the interior layers of a SXnMXnS where n can be 0 to 3 (where S indicates a spunbond layer, M indicates a melt blown layer and X may be either a spun bond or a melt blown layer, and n can be 0 to 3). It was thought that exposing such lower melting melt blown fibers to the pressure and temperatures typically encountered during the bonding stage of the spunbond nonwoven process, a film-like structure could be formed, such that the breathability and barrier properties of such a structure could be tailored to the application.
Accordingly the present invention relates to a multilayer nonwoven structure comprising at least two spun bond layers and at least one easily meltable layer wherein the easily meltable layer is located between the at least two spunbond layers, and where the easily meltable layer is comprised of a polymer having a melting point less than the melting point of the polymer which comprises the outer surface of the fibers which comprise the meltblown or spun bond layers which are not intended to be melted.
The present invention allows a more textile-like article with the same containment as a film-nonwoven laminate to be produced, but with better haptics, equivalent breathability, and lower manufacturing costs.